Question: Daniel is 5 times as old as Luis and is also 8 years older than Luis. How old is Luis?
Explanation: We can use the given information to write down two equations that describe the ages of Daniel and Luis. Let Daniel's current age be $d$ and Luis's current age be $l$ $d = 5l$ $d = l + 8$ Now we have two independent equations, and we can solve for our two unknowns. Since we are looking for $l$ , and both of our equations have $d$ alone on one side, this is a convenient time to use elimination. Subtracting the second equation from the first equation, we get: $0 =$ $5l$ $-$ $ (l + 8)$ which combines the information about $l$ from both of our original equations. Solving for $l$ , we get: $4 l = 8$ $l = 2$.